This invention relates generally to processes and apparatuses for restoring color film, and, in particular embodiments, to a process for restoring color of motion picture color negative film.
Color negative film has been a popular recording medium for decades. However, color films, especially those produced in the early stages of color film technology, tend to fade over time. For color image restoration processes, this is especially problematic with motion picture color negative film, wherein thousands of images may be found on a single reel of film. Significant fading of motion picture color negative film has been known to occur in as little as ten years. Fading tends to occur primarily in the blue layer and somewhat in the green layer. The unstable blue layer often fades such that the highlights and shadow areas (D-Max and D-Min) are close to each other in density and present a false color of the original image. So, for example, a color negative from the 1950""s may now provide a somewhat soupy green appearance, when printed using, for example, Laboratory Aim Densities, which were established by Eastman Kodak. Laboratory Aim Density is a control for standardizing color reproduction.
Another example of color deterioration that tends to occur in color negative films is a fading in which the highlights or white areas appear yellow, while the shadow or dark areas of the image appear blue. This fading characteristic, known as crossover, can prevent an image produced from an original negative from being true to the correct color.
One process for restoring color of faded or discolored color photographs (not of negatives) is by chemically treating the photographs (see U.S. Pat. No. 4,717,646). In that process, faded or discolored color photographs are cleaned with a water-free application of anhydrous acetone-free diacetone and coated with a color corrective restoration solution. Exposing certain old photographs or other film media to chemical treatments, however, may not be favored because of the risk of damaging or destroying the media.
Today, typically color negatives are protected by striking an interpositive from the original negative. A duplicate negative can be created from the interpositive. New projection prints created from the duplicate negative can be equal in quality to those generated from the original negative. However, negatives that, for example, are over 30 years old may no longer be capable of being restored to their original colors. Even basic enhancement through the interpositive to duplicate negative process typically is substantially ineffective in restoring the original colors. While it may be possible to correct the light areas with the interpositive to duplicate negative process, the process tends to cause the dark areas to become discolored into the blue range.
Another way to preserve color film negatives is to create three black and white negatives bearing a red, blue and green image of the color film negative, respectively. Since black and white film tend to last longer, this method can be effectively used to recreate new color negatives. This method, however, is not useful where the original film was not preserved in this manner.
The inventor herein had a prior method of restoring faded color negatives outlined in the SMPTE Journal, May 1997, pp. 281-284. This method proved to be too awkward and costly since it requires significant changes to normal laboratory procedures.
Computerized scanning systems permit film to be scanned, and then digitally altered and enhanced. However, digital enhancement continues to remain expensive, and results in a digital output, rather than a film output.
Therefore, there exists a need for a cost-effective method and system for restoring color negative film which has faded over time, without the need to expose the original negatives to chemicals or expensive mechanical or digital processing.
In accordance with the present invention, a process for restoring color of a color negative (e.g., a copy of an original negative), motion picture color negative film (for example, 16 mm, 35 mm, 70 mm and other motion picture color negative film produced by the Eastman Kodak Co., Fuji, Agfa, and others), and other types of film.
In one aspect of the invention, the process comprises the steps of making red, green and blue separations and then recombining them to form a color enhanced internegative or interpositive.
In another aspect, the invention comprises the following steps:
Step 1: From the original faded color negative, print onto orthochromatic film stock that is sensitive only to blue and A green light, such as Eastman Direct MP Film Type 5360, using green light. This will create a black and white enhancement mask record of green information with a negative image (xe2x80x9cgreen 5360xe2x80x9d.) From the original faded color negative, additionally print onto orthochromatic film stock using blue light. This will create a black and white enhancement mask record of blue information with a negative image (xe2x80x9cblue 5360xe2x80x9d).
Step 2: From the original color negative, make a standard red separation on standard separation stock. From the original color negative, print a pass of green light onto separation stock (to create a standard green separation), then a second pass using the green 5360 enhancement mask onto the same piece of separation stock in sync. The exposure from the green 5360 enhancement mask helps in improving the density of the final improved green separation. From the original color negative, print a pass of blue light onto separation stock (to create a standard blue separation), then a second pass using the blue 5360 enhancement mask onto the same piece of separation stock in sync. The exposure from the blue 5360 enhancement mask helps in improving the density of the final blue separation. It is on the improved green and blue separations that the improvement of color has taken place.
Step 3: Finally, take the resulting red, and improved green and blue (RGB) separations and recombine them on to color internegative film to create a final internegative from which color prints can be struck.
The inventor has found that in many cases, the green record fades less than the blue record, so it may not always be necessary to create a separate enhanced green separation.
In another embodiment of the process, the original faded negative is first used to make a single black and white record of the faded green and blue record of the original negative. This can be done by using an orthochromatic film that is only sensitive to blue and green light, such as Eastman Direct MP Film Type 5630 (xe2x80x9c5360xe2x80x9d). The 5360 separates the green and blue records (the records which fade) and provides a way of increasing density without increasing grain by way of a second pass from the 5360 element on the separations, thereby rebalancing the color information.
Next, the separations are made. Once the 5360 element has been made form the original negative, it is then run as a separate pass while making the separations of the original faded negative on a contact printer for the single green and blue separations (e.g., using a pass with green light to create a green separation, and a pass with blue light to create a blue separation.) This will give increased density to the green and blue separations. The red separation is made from the original faded negative using standard black and white separation film stock (since fading does not occur in the red record). Once the red separation and enhanced blue and green separations are made, they can be recombined at any later time to make a renewed internegative with enhanced color.
In a further embodiment of the invention, color prints and interpositives can be made on a registration contact printer or other types of printers. In this embodiment, the original faded color negative is taken, and is overlaid onto orthochromatic film stock that is sensitive only to blue and green light, such as Eastman Direct MP Film Type 5360. Using blue light, a blue 5360 autopositive mask is made. Next, from the original negative, one pass of the original negative is printed onto intermediate stock, which can be color print stock or interpositive stock using a strong yellow light so that the resulting image appears very blue in the mid-tones and shadow areas and the highlights appear neutral in color. Next, a second pass is printed in tri-pack (the tri-pack being the intermediate stock printed in the first pass, the original negative and the blue 5360 autopositive mask) by combining the three films in a contact printer using a strong blue light. The result is that the intermediate stock will have an additional exposure with the blue 5360 autopositive mask and the original negative. This creates yellow light in the shadows and mid-tones, thus neutralizing the blue cast and making the final image appear normal. Thus, a color enhanced color print or interpositive will be created.
In yet a further embodiment of the invention, color prints and interpositives can be made on a registration contact printer or other types of printers using a bi-pack process. In this embodiment, the original faded color negative is taken, and is overlaid onto orthochromatic film stock that is sensitive only to blue and green light, such as Eastman Direct MP Film Type 5360. Using blue light, a blue 5360 autopositive mask is made. Next, the original negative is bi-packed with intermediate stock (either color print film or interpositive film) and is exposed with yellow biased light, and preferably strong yellow light. In a second pass, the 5360 autopositive film is overlaid on the intermediate stock previously exposed in the first pass, and is exposed with blue light to create a color enhanced print (when print film is used) and a color enhanced interpositive (when intermediate film is used).
The above discussed and many other features and attendant advantages of the present invention will become better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings.